A metallic element crystallizes into a lattice containing a sequence of layers of ABABAB ............ Any packing of spheres leaves out voids in the lattice. The percentage by volume of empty space of this is

(1) 26%

(2) 21%

(3) 18%

(4) 16 %

Concept Questions :-

Introduction and Type of Crystal System
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Silver metal crystallises in a cubic closest – packed arrangement with the edge of the unit cell having a length a = 407 pm. What is the radius of silver atom.

(1) 143.9 pm

(2) 15.6 pm

(3) 11.59 pm

(4) 13.61 pm

Concept Questions :-

Introduction and Type of Crystal System
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From the fact that the length of the side of a unit cell of lithium is 351 pm. Calculate its atomic radius. Lithium forms body centred cubic crystals.

(1) 152.69 pm

(2) 62.71 pm

(3) 151.98 pm

(4) 54.61 pm

Concept Questions :-

Introduction and Type of Crystal System
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Atomic radius of silver is 144.5 pm. The unit cell of silver is a face centred cube. Calculate the density of silver.

(1) 10.50 g/cm3

(2) 16.50 g/cm3

(3) 12.30 g/cm3

(4) 15.50 g/cm3

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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Lithium borohydride (LiBH4),crystallises in an orthorhombic system with 4 molecules per unit cell. The unit cell dimensions are : a = 6.81Å, b= 4.43Å, c=7.17Å. If the molar mass of LiBH4 is 21.76 g mol–1. The density of the crystal is –

(1) 0.668 g cm–3

(2) 0.585 g cm2

(3) 1.23 g cm–3

(4) None

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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A metallic elements exists as a cubic lattice. Each edge of the unit cell is 2.88Å. The density of the metal is 7.20 g cm–3. How many unit cells will be present in 100 gm of the metal.

(1) 5.82 × 1023

(2) 6.33 × 1023

(3) 7.49 × 1024

(4) 6.9 × 1024

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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Silver crystallizes in a face centred cubic system, 0.408 nm along each edge. The density of silver is 10.6 g/cm3 and the atomic mass is 107.9 g/mol. Calculate Avogadro's number.

(1) 6.00×1023 atom/mol

(2) 9.31×1023 atom/mol

(3) 6.23×1023 atom/mol

(4) 9.61×1023atom/mol

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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Fraction of total volume occupied by atoms in a simple cube is

(1) π2

(2) 3π8

(3) 2π6

(4) π6

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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A solid AB has the NaCl structure. If radius of cation A+ is 120 pm, calculate the maximum possible value of the radius of the anion B

(1) 240 pm

(2) 280 pm

(3) 270 pm

(4) 290 pm

Concept Questions :-

Voids and radius ratio/coordination number
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CsBr has a (bcc) arrangement and its unit cell edge length is 400 pm. Calculate the interionic distance in CsCl [CBSE 1993]

(1) 346.4 pm

(2) 643 pm

(3) 66.31 pm

(4) 431.5 pm

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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